Step 1: Understanding the Concept:
This question tests knowledge of ornamental trees and their flower colors.
Step 2: Detailed Explanation:
Delonix regia (A):
Also known as Gulmohar or Flame tree.
Flowers are orange-red to scarlet.
Thus, A has orange-colored flowers.
Saraca indica (B):
Also known as Ashoka tree.
Flowers are orange-yellow to orange-red.
Thus, B has orange-colored flowers.
Cassia siamea (C):
Also known as Siamese cassia.
Flowers are yellow.
Thus, C does not have orange-colored flowers.
Butea monosperma (D):
Also known as Flame of the Forest.
Flowers are orange-red to red.
Thus, D has orange-colored flowers.
Bauhinia purpurea (E):
Also known as Purple orchid tree.
Flowers are purple to pink.
Thus, E does not have orange-colored flowers.
Step 3: Final Answer:
Thus, the trees with orange-coloured flowers are A (Delonix regia), B (Saraca indica), and D (Butea monosperma).
However, option D states "A, B and D Only" which is correct.
Thus, the correct answer is option (D).
[0.5cm]